On the whole, the rise of nationalism, which was the most striking development during the administration of Phibunsonggram, had its roots in the traditional Thai love of independence.
King Rama VI was
the father of modern Thai nationalism
It had grown through struggle with European powers and through Chinese and European competition within the country. It had been fostered by King Rama VI(191031925), whose policy was reaffirmed by the constitutional regime from 1932.
Premier Phibunsonggram and his followers, especially Luang Vichitr Vadakarn, considered the king to be the father of modern Thai nationalism, and sought to emulate his policy.
However, nationalism assumed a new dimension; it took the forms of “Pan-Thaiism” and “ irredentism”, strengthened by the increased build-up of the armed forces on which, from 1938 onwards, the Thai government devoted nearly on-third of its budget resources.